/** @file * @brief DNS resolving library * * An API for applications to resolve a DNS name. */ /* * Copyright (c) 2017 Intel Corporation * * SPDX-License-Identifier: Apache-2.0 */ #ifndef ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_ #define ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_ #include #include #ifdef __cplusplus extern "C" { #endif /** * @brief DNS resolving library * @defgroup dns_resolve DNS Resolve Library * @ingroup networking * @{ */ /** * DNS query type enum */ enum dns_query_type { DNS_QUERY_TYPE_A = 1, /* IPv4 */ DNS_QUERY_TYPE_AAAA = 28 /* IPv6 */ }; #ifndef DNS_MAX_NAME_SIZE #define DNS_MAX_NAME_SIZE 20 #endif /* Make sure that we can compile things even if CONFIG_DNS_RESOLVER * is not enabled. */ #if !defined(CONFIG_DNS_RESOLVER_MAX_SERVERS) #define CONFIG_DNS_RESOLVER_MAX_SERVERS 1 #endif #if !defined(CONFIG_DNS_NUM_CONCUR_QUERIES) #define CONFIG_DNS_NUM_CONCUR_QUERIES 1 #endif /* If mDNS is enabled, then add some extra well known multicast servers to the * server list. */ #if defined(CONFIG_MDNS_RESOLVER) #if defined(CONFIG_NET_IPV6) && defined(CONFIG_NET_IPV4) #define MDNS_SERVER_COUNT 2 #else #define MDNS_SERVER_COUNT 1 #endif /* CONFIG_NET_IPV6 && CONFIG_NET_IPV4 */ #else #define MDNS_SERVER_COUNT 0 #endif /* CONFIG_MDNS_RESOLVER */ /* If LLMNR is enabled, then add some extra well known multicast servers to the * server list. */ #if defined(CONFIG_LLMNR_RESOLVER) #if defined(CONFIG_NET_IPV6) && defined(CONFIG_NET_IPV4) #define LLMNR_SERVER_COUNT 2 #else #define LLMNR_SERVER_COUNT 1 #endif /* CONFIG_NET_IPV6 && CONFIG_NET_IPV4 */ #else #define LLMNR_SERVER_COUNT 0 #endif /* CONFIG_MDNS_RESOLVER */ #define DNS_MAX_MCAST_SERVERS (MDNS_SERVER_COUNT + LLMNR_SERVER_COUNT) /** * Address info struct is passed to callback that gets all the results. */ struct dns_addrinfo { struct sockaddr ai_addr; socklen_t ai_addrlen; u8_t ai_family; char ai_canonname[DNS_MAX_NAME_SIZE + 1]; }; /** * Status values for the callback. */ enum dns_resolve_status { DNS_EAI_BADFLAGS = -1, /* Invalid value for `ai_flags' field */ DNS_EAI_NONAME = -2, /* NAME or SERVICE is unknown */ DNS_EAI_AGAIN = -3, /* Temporary failure in name resolution */ DNS_EAI_FAIL = -4, /* Non-recoverable failure in name res */ DNS_EAI_NODATA = -5, /* No address associated with NAME */ DNS_EAI_FAMILY = -6, /* `ai_family' not supported */ DNS_EAI_SOCKTYPE = -7, /* `ai_socktype' not supported */ DNS_EAI_SERVICE = -8, /* SRV not supported for `ai_socktype' */ DNS_EAI_ADDRFAMILY = -9, /* Address family for NAME not supported */ DNS_EAI_MEMORY = -10, /* Memory allocation failure */ DNS_EAI_SYSTEM = -11, /* System error returned in `errno' */ DNS_EAI_OVERFLOW = -12, /* Argument buffer overflow */ DNS_EAI_INPROGRESS = -100, /* Processing request in progress */ DNS_EAI_CANCELED = -101, /* Request canceled */ DNS_EAI_NOTCANCELED = -102, /* Request not canceled */ DNS_EAI_ALLDONE = -103, /* All requests done */ DNS_EAI_IDN_ENCODE = -105, /* IDN encoding failed */ }; /** * @typedef dns_resolve_cb_t * @brief DNS resolve callback * * @details The DNS resolve callback is called after a successful * DNS resolving. The resolver can call this callback multiple times, one * for each resolved address. * * @param status The status of the query: * DNS_EAI_INPROGRESS returned for each resolved address * DNS_EAI_ALLDONE mark end of the resolving, info is set to NULL in * this case * DNS_EAI_CANCELED if the query was canceled manually or timeout happened * DNS_EAI_FAIL if the name cannot be resolved by the server * DNS_EAI_NODATA if there is no such name * other values means that an error happened. * @param info Query results are stored here. * @param user_data The user data given in dns_resolve_name() call. */ typedef void (*dns_resolve_cb_t)(enum dns_resolve_status status, struct dns_addrinfo *info, void *user_data); /** * DNS resolve context structure. */ struct dns_resolve_context { struct { /** DNS server information */ struct sockaddr dns_server; /** Connection to the DNS server */ struct net_context *net_ctx; /** Is this server mDNS one */ u8_t is_mdns : 1; /** Is this server LLMNR one */ u8_t is_llmnr : 1; } servers[CONFIG_DNS_RESOLVER_MAX_SERVERS + DNS_MAX_MCAST_SERVERS]; /** This timeout is also used when a buffer is required from the * buffer pools. */ s32_t buf_timeout; /** Result callbacks. We have multiple callbacks here so that it is * possible to do multiple queries at the same time. */ struct dns_pending_query { /** Timeout timer */ struct k_delayed_work timer; /** Back pointer to ctx, needed in timeout handler */ struct dns_resolve_context *ctx; /** Result callback */ dns_resolve_cb_t cb; /** User data */ void *user_data; /** TX timeout */ s32_t timeout; /** String containing the thing to resolve like www.example.com */ const char *query; /** Query type */ enum dns_query_type query_type; /** DNS id of this query */ u16_t id; } queries[CONFIG_DNS_NUM_CONCUR_QUERIES]; /** Is this context in use */ bool is_used; }; /** * @brief Init DNS resolving context. * * @details This function sets the DNS server address and initializes the * DNS context that is used by the actual resolver. DNS server addresses * can be specified either in textual form, or as struct sockaddr (or both). * Note that the recommended way to resolve DNS names is to use * the dns_get_addr_info() API. In that case user does not need to * call dns_resolve_init() as the DNS servers are already setup by the system. * * @param ctx DNS context. If the context variable is allocated from * the stack, then the variable needs to be valid for the whole duration of * the resolving. Caller does not need to fill the variable beforehand or * edit the context afterwards. * @param dns_servers_str DNS server addresses using textual strings. The * array is NULL terminated. The port number can be given in the string. * Syntax for the server addresses with or without port numbers: * IPv4 : 10.0.9.1 * IPv4 + port : 10.0.9.1:5353 * IPv6 : 2001:db8::22:42 * IPv6 + port : [2001:db8::22:42]:5353 * @param dns_servers_sa DNS server addresses as struct sockaddr. The array * is NULL terminated. Port numbers are optional in struct sockaddr, the * default will be used if set to 0. * * @return 0 if ok, <0 if error. */ int dns_resolve_init(struct dns_resolve_context *ctx, const char *dns_servers_str[], const struct sockaddr *dns_servers_sa[]); /** * @brief Close DNS resolving context. * * @details This releases DNS resolving context and marks the context unusable. * Caller must call the dns_resolve_init() again to make context usable. * * @param ctx DNS context * * @return 0 if ok, <0 if error. */ int dns_resolve_close(struct dns_resolve_context *ctx); /** * @brief Cancel a pending DNS query. * * @details This releases DNS resources used by a pending query. * * @param ctx DNS context * @param dns_id DNS id of the pending query * * @return 0 if ok, <0 if error. */ int dns_resolve_cancel(struct dns_resolve_context *ctx, u16_t dns_id); /** * @brief Resolve DNS name. * * @details This function can be used to resolve e.g., IPv4 or IPv6 address. * Note that this is asynchronous call, the function will return immediately * and system will call the callback after resolving has finished or timeout * has occurred. * We might send the query to multiple servers (if there are more than one * server configured), but we only use the result of the first received * response. * * @param ctx DNS context * @param query What the caller wants to resolve. * @param type What kind of data the caller wants to get. * @param dns_id DNS id is returned to the caller. This is needed if one * wishes to cancel the query. This can be set to NULL if there is no need * to cancel the query. * @param cb Callback to call after the resolving has finished or timeout * has happened. * @param user_data The user data. * @param timeout The timeout value for the query. Possible values: * K_FOREVER: the query is tried forever, user needs to cancel it manually * if it takes too long time to finish * >0: start the query and let the system timeout it after specified ms * * @return 0 if resolving was started ok, < 0 otherwise */ int dns_resolve_name(struct dns_resolve_context *ctx, const char *query, enum dns_query_type type, u16_t *dns_id, dns_resolve_cb_t cb, void *user_data, s32_t timeout); /** * @brief Get default DNS context. * * @details The system level DNS context uses DNS servers that are * defined in project config file. If no DNS servers are defined by the * user, then resolving DNS names using default DNS context will do nothing. * The configuration options are described in subsys/net/lib/dns/Kconfig file. * * @return Default DNS context. */ struct dns_resolve_context *dns_resolve_get_default(void); /** * @brief Get IP address info from DNS. * * @details This function can be used to resolve e.g., IPv4 or IPv6 address. * Note that this is asynchronous call, the function will return immediately * and system will call the callback after resolving has finished or timeout * has occurred. * We might send the query to multiple servers (if there are more than one * server configured), but we only use the result of the first received * response. * This variant uses system wide DNS servers. * * @param query What the caller wants to resolve. * @param type What kind of data the caller wants to get. * @param dns_id DNS id is returned to the caller. This is needed if one * wishes to cancel the query. This can be set to NULL if there is no need * to cancel the query. * @param cb Callback to call after the resolving has finished or timeout * has happened. * @param user_data The user data. * @param timeout The timeout value for the connection. Possible values: * K_FOREVER: the query is tried forever, user needs to cancel it manually * if it takes too long time to finish * >0: start the query and let the system timeout it after specified ms * * @return 0 if resolving was started ok, < 0 otherwise */ static inline int dns_get_addr_info(const char *query, enum dns_query_type type, u16_t *dns_id, dns_resolve_cb_t cb, void *user_data, s32_t timeout) { return dns_resolve_name(dns_resolve_get_default(), query, type, dns_id, cb, user_data, timeout); } /** * @brief Cancel a pending DNS query. * * @details This releases DNS resources used by a pending query. * * @param dns_id DNS id of the pending query * * @return 0 if ok, <0 if error. */ static inline int dns_cancel_addr_info(u16_t dns_id) { return dns_resolve_cancel(dns_resolve_get_default(), dns_id); } /** * @} */ #if defined(CONFIG_DNS_RESOLVER) /** * @brief Initialize DNS subsystem. */ void dns_init_resolver(void); #else #define dns_init_resolver(...) #endif /* CONFIG_DNS_RESOLVER */ #ifdef __cplusplus } #endif #endif /* ZEPHYR_INCLUDE_NET_DNS_RESOLVE_H_ */